The field of the invention is systems and methods for installing fiber optic cable or similar cables or conduits underground, and upgrading existing gas pipelines via installation of a new inner pipeline within the existing pipeline. More specifically, the invention relates to the installation of such cable or conduit or inner pipeline into pressurized pipelines, such as natural gas pipelines.
Natural gas utilities are constantly replacing and upgrading their distribution pipeline systems. These efforts are undertaken for a variety of reasons, including situations when the pipe""s useful life is reached, when demand requires that additional supplies be distributed or when improved pipeline materials become available. In many cases, a lower pressure pipeline system can be upgraded to a higher-pressure system by installation of higher pressure-rated or newer pipe with a substantially smaller diameter.
In urban areas, replacement or upgrade of distribution systems is especially problematic since open trenching costs are very high and public disruption significant. Alternatives to trenching include various methods for insertion of xe2x80x9ccasingxe2x80x9d into the existing pipelines. This process, while generally more acceptable than trenching, is also costly. Many casing methods require de-pressurization of the pipeline while the casing is being installed. This is costly to the utility and can disrupt service to substantial numbers of customers for extended time periods.
Accordingly, improved methods and systems are needed for replacing and upgrading existing pipeline systems.
In a first aspect of the invention, a method of installing a pipe inner duct into a pressurized pipeline includes the step of attaching a first air or pressure lock housing to the pressurized pipeline at a first location. A second air or pressure lock housing is attached to the pressurized pipeline at a second location. Duct rod or other translating member is preferably fed into the pipeline through a seal at the first location. The duct rod is pushed or routed to the second location.
A pipe inner duct is attached to the duct rod, at or adjacent to the second location, either inside or outside of the pipeline. The duct rod and the pipe inner duct are then pulled back to the first location and routed out of the pipeline.
A second and separate aspect of the invention includes the steps of attaching a first fitting to the pressurized pipeline at a first location. A first valve is attached to the first drilling fitting. A cutting or drilling tool is attached to the valve, and sealed against the valve. The valve is opened. A pipe cutter of the cutting tool is extended through the open valve to cut or drill a hole into the pressurized pipeline through the first fitting. The fitting and pipe cutter are preferably perpendicular to the pipeline to better facilitate the drilling operation. The cutter is withdrawn and the valve is then closed. The cutting tool is preferably removed.
A first air lock housing is installed on the first valve. The valve is opened and the pressure is equalized between the first air lock housing and the pressurized pipeline. A guide ball or similar duct rod end guide is optionally attached onto the end of the duct rod using a first manipulator in the first air lock housing.
A second fitting is attached to the pressurized pipeline at a second location. The exit port of the second drilling fitting is sealed. A second valve is attached to the second fitting. A cutting or drilling tool is attached and sealed against the valve. The valve is opened. A cutter is extended from the cutting tool and a hole is cut or drilled into the pressurized pipeline through the second fitting. The cutter is withdrawn and the valve is closed. A second air lock housing is installed on the second drilling fitting. The second valve is opened and pressure is equalized. A duct rod or other translating member is pushed along inside of the pressurized pipeline to the second fitting. At the second fitting, the guide ball or other rod end guide, if any, is removed from the duct rod, for example using a second manipulator. The duct rod is attached to a pipe inner duct. The duct rod and the pipe inner duct are pulled back through the pipeline. Alternatively, once the duct rod is routed between the first and second air lock housings, the pipe inner duct can be attached to duct rod outside of the first air lock housing and the duct rod can be pulled forward from the second air lock housing, to route the pipe inner duct through the pipeline.
The pipe inner duct then provides a new pipeline within the existing pipeline.
The methods and apparatus allow for the installation of a new inner pipeline within an existing pressurized pipeline, such as a gas pipeline, without requiring any shutoff or interruption in service. In addition, no bypass pipeline is needed to maintain service to customers connected to the pipe section where the new inner pipeline is being installed. The methods are suitable for both metal and plastic pipelines. Excavation or trenching to replace the existing pipeline or to lay a new pipeline, is avoided.
The invention resides as well in sub-combinations of the methods and systems described. The tools and fittings described also constitute separate inventions to be claimed, apart from systems and methods. These items may also be provided as a kit.
It is an object of the invention to provide a method and system for installing a pipe inner duct into existing pressurized (e.g., gas) pipelines without interrupting the flow in the pipeline, to provide a new pipeline within the existing pipeline.
The following brief and detailed descriptions of the drawings refer to installation of cable and conduit. It will be clear with reference to the discussion of FIG. 16 that the description of installation of cable or conduit applies as well to the installation of an inner duct within an existing pipeline.